GULLABLE0NE Posted November 17, 2008 Share Posted November 17, 2008 Well I will be buying my AP soon and i'm curious what differences there are between the 91 octane maps for stage 1 & 2 and the 93 octane maps for stage 1 & 2? what are the hp/tq differences if any? any changes in milage between the different octanes? Also a little off topic but still involving the AP. When running maps from the AP does the SI drive still work (change throttle response) or does the aP discard that feature? Link to comment Share on other sites More sharing options...
izzy Posted November 17, 2008 Share Posted November 17, 2008 The si drive still functions normally. Link to comment Share on other sites More sharing options...
Spec B Posted November 17, 2008 Share Posted November 17, 2008 The 93 octane map will be slightly more agressive than a 91 octane tune. How much hp/tq difference is anyones guess, I would guess 7-8 at stage 2..just a guess. Link to comment Share on other sites More sharing options...
GULLABLE0NE Posted November 18, 2008 Author Share Posted November 18, 2008 not bad i guess. i didn't think you'd get even that much from 91 to 93 Link to comment Share on other sites More sharing options...
Spec B Posted November 18, 2008 Share Posted November 18, 2008 According to Cobb, looks like about 5 crank HP for STI Stage 1. http://www.cobbtuning.com/images_products/3733.jpg Link to comment Share on other sites More sharing options...
DrCloud Posted November 19, 2008 Share Posted November 19, 2008 Here's a related question: At higher elevations (Denver, for example) 91 octane is the highest generally available. This has to do with the lower air density and the "natural" need to retard ignition just a bit (I think I'm saying this right, but I'm not certain). Although all vehicles lose a little performance, in Denver 91 octane behaves pretty much as 93 does at sea level. So, do you Denver people with APs use only the 91 maps? Or what? I've noticed that one of the other vendors offers maps tuned to different elevations. Are those better out there? (I'm interested because although both our cars are now at sea level, one may migrate upward soon, and the AP with it.) Thanks, HPH Link to comment Share on other sites More sharing options...
Spec B Posted November 19, 2008 Share Posted November 19, 2008 Here's a related question: At higher elevations (Denver, for example) 91 octane is the highest generally available. This has to do with the lower air density and the "natural" need to retard ignition just a bit (I think I'm saying this right, but I'm not certain). Although all vehicles lose a little performance, in Denver 91 octane behaves pretty much as 93 does at sea level. I am not sure I follow.. No matter what the elevation, 93 is better than 91. Link to comment Share on other sites More sharing options...
Spec B Posted November 19, 2008 Share Posted November 19, 2008 Grabbed this from wikipedia: In the Rocky Mountain (high altitude) states, 85 octane is the minimum octane and 91 is the maximum octane available in fuel. The reason for this is that in higher-altitude areas, a typical combustion engine draws in less air per cycle due to the reduced density of the atmosphere. This directly translates to reduced absolute compression in the cylinder, therefore deterring knock. It is safe to fill up a car with a carburetor that normally takes 87 AKI fuel at sea level with 85 AKI fuel in the mountains, but at sea level the fuel may cause damage to the engine. A disadvantage to this strategy is that most turbocharged vehicles are unable to produce full power, even when using the "premium" 91 AKI fuel. Link to comment Share on other sites More sharing options...
alaskajoel Posted November 19, 2008 Share Posted November 19, 2008 Grabbed this from wikipedia: In the Rocky Mountain (high altitude) states, 85 octane is the minimum octane and 91 is the maximum octane available in fuel. The reason for this is that in higher-altitude areas, a typical combustion engine draws in less air per cycle due to the reduced density of the atmosphere. This directly translates to reduced absolute compression in the cylinder, therefore deterring knock. It is safe to fill up a car with a carburetor that normally takes 87 AKI fuel at sea level with 85 AKI fuel in the mountains, but at sea level the fuel may cause damage to the engine. A disadvantage to this strategy is that most turbocharged vehicles are unable to produce full power, even when using the "premium" 91 AKI fuel. That's why i mix it with e85 here in Utah Link to comment Share on other sites More sharing options...
DrCloud Posted November 19, 2008 Share Posted November 19, 2008 Right -- 93 will perform better but isn't available. But the question is really which map to use. I suppose the Stage I 91 octane map is the right answer, but I'm checking because of the elevation's effect on everything. HPH Link to comment Share on other sites More sharing options...
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